The generally accepted answer is around 1720 by Cristofori who invented the hammer escapement action, where hammers strike the strings and there is control over dynamics.
There were a lot of innovations that occurred over then next century and a half. The grand piano, with a cast iron frame, trichord treble strings, modern action, overstrung, copper wrapped bass strings, as we know it today was pretty much standardized by the mid to late 1800s
From:
http://au.answers.Yahoo.com/question/index?qid=20080531012751AAhRXrr
The grand piano was invented in 1720 by an Italian named Bartolomeo Cristofori. The word piano is an abbreviation of pianoforte.
The first piano was made c.1709 by Bartolomeo Cristofori
The grand piano was invented in Florence, Italy in the early 18th century by Bartolomeo Cristofori.
The concert piano doesn't have as nice sound as the baby grand piano.
The Upright Piano was invented in 1826.
A piano has many different shapes but the main three are the upright, the grand and the baby grand piano.
the first piano was invented by bartolomeo cristofori
A grand piano makes sound by a mechanical system: little hammers hitting strings when the keys are pressed. An electric piano produces sound much the same way, except the sounds are turned into electronic signals by pickups, which makes it able to be amplified or recorded.
Phillip Jin Kim
No, nothing can compare to a grand piano.
Yes they are. Bosendorfer piano has 97notes while grand piano has 88notes.
The concert piano doesn't have as nice sound as the baby grand piano.
PH Grand Piano was created in 1931.
More Grand Piano was created in 1985.
Surprisingly, the cost of a Grand Piano in the 1930'S was about a grand ($1,000.00).
giraffes invented the giraffe piano
The Upright Piano was invented in 1826.
A piano has many different shapes but the main three are the upright, the grand and the baby grand piano.
The Grand Piano is in the Pizza Shop in the Plaza.
the first piano was invented by bartolomeo cristofori